Fin / Slot Question

Glue a ring at the base and fill the hole with epoxy and a substrate.

Use a thick ring at the rear.

Use a ring and a coupler.

Just Tech Jerry again.

I have actually seen where they don't do anything with them. If you wanted to get really fancy, you could always put tabs in the aft centering rings to match the slots.

Depending on rocket diameter and glue used.

Example:

0-1.5" rocket diameter, paper, yellow glue 1.5-3" fiberglass and epoxy 3-12" layering strategy inside and out with fiberglass and epoxy by installing rear ring last.

Divots can be filled with bondo(strong) or spackle (easy).

Jerry,

I tried that the other day at my golf course, but they somehow weren't happy with the results...

David Erbas-White

I just fill it with a piece of the slot I cut out, or from another body tube scrap, using CA, epoxy, or fiberglass depending upon the stress involved. Had to use a Saranwrap covered coupler "jig" to do this on a gap staged model; the slots aft of the TTMM fin root were an inch long.

Or, cut 1/4" off the back of the body tube. :)

If your fins are properly mounted between two centering rings, there will be little to no stress on this little piece. All you need is enough glue to keep it from falling off.

I leave it open, use a fincan and make it a rear ejection rocket.

Mark Simpson NAR 71503 Level II God Bless our peacekeepers

I try to make my multi-stage couplings as strong and heat resistant as possible. The aft centering ring of the sustainer is recessed a caliber forward to accomodate the booster's coupler. I usually epoxy/FG the slot repairs on TTMM fin sustainer bodies for that reason. But, mainly, I'm worried about landings and protecting the tail/fins on single stage rockets. Most of my rockets have no sweep in their somewhat forward mounted fins. I build em to land tail first (not fin first) and the tube end takes the brunt of the impact. CA/PVA slot repairs work on light models and I use epoxy/FG for heavier models and clusters. A layer of epoxy is also nice to have when I load things up too close to the blast deflector.

I use TTW/TTMM fins, epoxy, fiberglass, and heavy duty construction techniques on almost all my rockets (not hi-perf), even sport model A and B motor birds. My first BAR rocket is dinged, scratched, and well-cooked on the inside, but still flies great with the original fins. Not all of em survive accidents and hard landings, but most do. Or they are easily repaired.

Except when they catch fire or land in the lake. ;)

Thanks for the replies everyone. I went with Gary's suggestion and cut a

1/4" off the end of the tube. This was not easy to do, since I'm dealing with 4" Quantum Tube and the fin slots are 13+ inches long. The tube ends flap all over the place. What I did was support the inside with a 1/2" thick centering ring, supported the O.D. with a 4" hose clamp, and buzzed those babies off with my compound miter saw. Worked like a charm. That'll will cure me of cutting my fin slots too long again!

-- Joe Michel NAR 82797 L1